Quick-acting release for a normally locked lid of an emergency smoke duct

ABSTRACT

A lid is so supported at an open end of an emergency smoke duct as to tend gravitationally to turn to an open position. A lock mechanism mounted on the back of the lid for normally holding same in a closed position includes a spring-loaded latch for engagement with a roller supported on an interior surface of the duct. In the event of a fire the latch is caused to move out of engagement with the roller by the manual pull of a chain extending through the lid, whereupon the lid turns by gravitation to its open position to permit the smoke and gases of combustion to escape through the duct. The latch may be made of magnetic material so that it will be automatically moved out of engagement with the roller upon energization of a solenoid.

United States Patent [191 Nozawa 1 Apr.2, 1974 QUICK-ACTING RELEASE FORA NORMALLY LOCKED LID OF AN EMERGENCY SMOKE DUCT [75] Inventor: KenjiNozawa, Tokyo, Japan [73] Assignee: Ryowa Choon Kogyo Kabushiki Kaisha,Tokyo, Japan [22] Filed: Nov. 28, 1972 [2|] Appl. No.: 310,140

[52] U.S. Cl 98/42, 49/2, 292/144 [51] Int. Cl E05f 15/20 [58] Field ofSearch 98/1, 42, 43; 49/2, 386; 292/144 X, 201, 142; 52/1, 200

[56 References Cited UNITED STATES. PATENTS 282,822 8/1883 Willard 98/423,383,811

5/1968 Ades 49/394 Xv Primary Examiner-William E. Wayner Attorney,Agent, or FirmGeorge B. Oujevolk [57] ABSTRACT A lid is so supported atan open end of an emergency smoke duct as to tend gravitationally toturn to an open position. A look mechanism mounted on the back of thelid for normally holding same in a closed position includes aspring-loaded latch for engagement with a roller supported on aninterior surface of the duct. 1n the event of a tire the latch is causedto move out of engagement with the roller by the manual pull of a chainextending through the lid, whereupon the lid turns by gravitation to itsopen position to permit the smoke and gases of combustion to escapethrough the duct. The latch may be made of magnetic material so that itwill be automatically moved out of engagement with the roller uponenergization of a solenoid.

14 Claims, 12 Drawing Figures PATENIEIJAPR 2 I974 .SHiET 1 [1F 5 FIG. I

36b 0 L38 I FIG. 4

FIG 2 PATENTEDAPR 2mm 3'800 687 sumu nr 5 PATENIEUAPR 2 m4 SHEET 5 [IF 5FIG. l2

1 QUICK-ACTING RELEASE FOR A NORMALLY LOCKED LID OF AN EMERGENCY SMOKEDUCT v BACKGROUND OF THE INVENTION smoke and harmful gases of combustionwhen a fire takes place in the building. Even in the early stage of thefire, in which only a narrowly limited portion of the building isactually caught by the flames, the smoke and harmful combustion gasesare known to take a heavy toll of its inhabitants.

This damage can be minimized, at least in part, by the provision ofemergency smoke ducts communicating the confined spaces of the buildingwith the atmosphere. The emergency-smoke ducts may be operativelyassociated with a blower or blowers to cause discharge of the smoke andcombustion gases from such confined spaces. It is necessary in this kindof smoke ducts that their ends open to the various enclosed spaces ofthe building be normally closed by lids which are readily openable inthe event of a fire. Conventionally, however, no simple and inexpensivemeans have been provided to facilitate the opening operation of thelids, and they have had to be mostly opened by the sheer manual force ofthe operator. Where attempts have been made to open the lids from adistant position, bulky and complex mechanisms have been required and,worse yet, their performance have not been absolutely reliable.

SUMMARY OFTHE INVENTION It is, therefore, an object of this invention toprovide a simple and inexpensive apparatus for quickly opening a lidclosing an open end of an emergency smoke duct to cause discharge ofsmoke and gases of combustion from enclosed spaces in the event of afire.

Another object of the invention is to provide an apparatus whichminimizes the exercise of a manual force necessary for opening the lidat an open end of an emergency smoke duct, so that the lid is easilyopenable even from a distant position.

A further object of the invention is to provide an apparatus such thatthe lid at an open end of an emergency smoke duct is readily openablemanually and/or electromagnetically.

A further object of the invention is to provide an apparatus includingmeans for preventing the lid from making oscillatory motion when turnedto an open position.

Still a further object of the invention is to provide an apparatusincluding means whereby the lid, after being once opened, can be easilyreturned to the initial condition, ready for the next opening operation.

Yet a further object of the invention is to provide an apparatus inwhich the impact of a dropped weight is utilized to open the lid quicklyand efficiently, with little exercise of a manual force.

With these objects in view and the other objects hereinafter madeapparent, the invention provides, in a ventilation system including asmoke duct having an end open to an enclosed space and a lid openablyclosing the open end of the smoke duct, an apparatus for quickly openingthe lid in the event of a fire which comprises support means forsupporting the lid at the open end of the smoke duct in such a mannerthat the lid tends gravitationally to turn to an open position. Lockmeans for normally holding the lid in a closed position includes a latchsupported on the back of the lid so as to be movable between a firstposition where the'latch engages a member supported on an interiorsurface of the smoke duct to hold the lid in the closed position and asecond position where the latch disengages the member to permit the lidto turn gravitationally to the open position, the latch beingspringloaded toward the first position. In the event of a fire the latchis moved to the second position against the spring load by release meanswhich may be actuated either manually or electromagnetically. In furtherembodiments of the invention the impact of a dropped weight is utilizedto move the latch to the second position.

The features which are believed to be novel and characteristic of thisinvention are set forth with particularity in the appended claims. Theinvention itself, however, both as to its construction and mode ofoperation, together with the further objects and advantages thereof,will be best understood from the following description of somepreferred' embodiments read in conjunction with the accompanyingdrawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a vertical sectional view ofa first preferred embodiment of the invention showing a lid in a closedposition, the view being taken along the plane of line 1-] in FIG. 2;

FIG. 2 is a horizontal sectional view taken along the plane of lineII-II in FIG. 1;

FIG. 3 is a view similar to FIG. 1 showing the lid in a closed position;

FIG. 4 is a vertical sectional view of a second preferred embodiment ofthe invention;

FIG. 5 is a vertical sectional view of a third preferred embodiment ofthe invention;

FIG. 6 is an enlarged, partly broken away side elevational view showinga weight and other means directly associated therewith in the FIG. 5embodiment;

FIG. 7 is an enlarged topplan view showing a pin adapted to releasablyhold the weight of FIG. 6 in an elevated position;

FIG. 8 is a vertical sectional view of a fourth preferred embodiment ofthe invention; I

FIG. 9 is an enlarged side elevational view showing some essential partsof the FIG. 8' emobidment in more detail;

FIG. 10 is a horizontal sectional view taken along the plane of line XXin FIG. 9;

FIG. 11 is a horizontal sectional view taken along the plane of lineXIXI in FIG. 9; and

FIG. 12 is a perspective view showing an alternative arrangement of aweight and other means directly associated therewith in the FIG. 8embodiment.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to the drawings,and in particular to FIGS. 1 to 3 thereof in order to describe a firstpreferred embodiment of this invention, a duct of any appropriate crosssectional shape, rectangular in this embodiment, is embedded in aceiling 102 or like horizontal overhead structures of a building todefine a passageway 100 through which smoke and gases of combustion areto be discharged in the event ofa fire. Typically made of sheet iron,the duct 10 is flanged at its lower end 11 to be bolted, as at 101, orotherwise secured to the ceiling 102. An open end 12, FIG. 3, of theduct 10 is normally closed by a lid 20 of corresponding shape which alsomay be made of sheet iron. This lid 20 is turnably supported at 13 by arod 21 secured at both ends thereof to the two opposed surfaces of theduct 10 and extending parallel to the other two opposed surfacesthereof. It may be noted that the rod 21 is further so disposed as todivide the lid 20 into two unequal rectangles, as best shown in FIG. 2,with the result that the lid tends gravitationally to turn to its vertical or open position shown in FIG. 3.

The numeral 30 in FIG. 2 generally indicates a lock mechanism mounted onthe larger portion 22 of the lid 20 on one side of the rod 21 fornormally holding the lid 20 in its horizontal or closed position. Thelock mechanism 30 includes a latch 31 in the form of a rod of iron orlike magnetic material extending through the hollow space of a solenod33. A pair of helical tension springs 32 extend between a stationarymember 34 and a movable member 35, the latter member being secured tothe left hand end 31a, as seen in FIGS. 1 and 2, of the latch 31, sothat the latch is resiliently urged to the right in the same drawings.When the solenoid 33 is energized, as upon depression of a push buttonswitch provided in a suitable position of the building, the latch 31acting as a plunger will be longitudinally displaced to the left, asindicated by the arrow in FIGS. 1 and 2, in spite of the tensile forceson the springs 32.

A bell crank 36 is swingably supported at its fulcrum 36a by a support37 fixedly mounted on the lid 20 intermediate between the left hand end31a of the latch 31 and a bore 23 formed through the lid 20 adjacent tothe rod 21. One end36b of this bell crank is linked to the end 31a ofthe latch 31 by a chain 38, whereas the other end 360 of the bell crankis connected to an elongate chain 40 extending downwardly through thebore 23 of the lid 20 and having a grip 41 at its lower extremity.

Means 50 for releasably engaging the end 31b of the latch 31 when thelid 20 is in its closed position is comprised of a bracket 51 secured tothe interior surface of the duct 10 and a roller 52 rotatably supportedthereby. When the end 31b of the latch 31 is disengaged from the roller52, either by the energization of the solenoid 33 or by the manual pullof the chain 40, so that the larger portion 22 of the lid 20 ispermitted to turn downwardly together with the lock mechanism 30, thelid 20 will swing to and fro in a pendulum fasion before becomingstationary in its vertical position shown in FIG. 3. This is preventedby means generally indicated by the numeral 60 in FIGS. 1 to 3. Themeans 60 comprises a first rod 61 and a second rod 62 foldably coupledto each other at 63, the first rod 61 being further tumably coupled at64 to the interior surface of the duct 10, and the second rod 62 beingtumably coupled at 65 to the upper surface of the lid 20.

Secured at 103 to the interior surface of the duct 10 is a microswitchhaving an actuating member 103a in such a position that its contactswill be held open as long as the lid 20 is in its closed position. Themicroswitch may be electrically associated with a blower and/or an alarmnot shown in the drawings. The aforesaid solenoid 33 may also beelectrically associated with a smoke or fire detector of well knownconstruction, not shown, in such a manner that the solenoid will beautomatically energized by the smoke or fire detector when same hasdetected a fire in accordance with the prior art.

The first preferred embodiment of the invention being constructedsubstantially as hereinbefore described, the solenoid 33 of the lockmechanism 30 will be energized immediately in the event of a fire,either automatically by the smoke or fire detector or manually by thedepression of the push button switch. The current-carrying solenoid 33causes the latch 31 to be longitudinally displaced in the direction ofthe arrow in FIGS. 1 and 2 in opposition to the tensile forces of thesprings 32, so that its end 31b becomes disengaged from the roller 52.The lid 20 is now free to turn clockwise, as indicated by the arrow inFIG. 1, on its fulcrum at 13, thus opening the duct 10 as it attains theposition of FIG. 3. The microswitch 103 is operated upon clockwise turnof the lid 20 to actuate the blower adapted to discharge the smoke andcombustion gases through the duct 10. The alarm may be set offsimultaneously to give audible, and perhaps visual, notice of the fire.It will be needless to say that the blower is connected to an electricalpower supply so made that its operation is unaffected by the fire.

It is also possible according to this invention for a person standingimmediately below the duct opening 20 to manually open the lid 20. Thiscan be accomplished simply by pulling the chain 40 connected to the end310 of the latch 31 through the bell crank 36 and the chain 38. Thelatch 31 will then be moved longitudinally out of engagement with theroller 52. Although the energization of the solenoid 33 and the manualpull of the chain 40 may take place simultaneously, the lid 20 willnevertheless be opened unfailingly because the two operations cause thesame motion of the latch 31. Upon clockwise turn of the lid 20, the rods61 and 62 become stretched as in FIG. 3 thereby preventing theoscillatory motion of the lid and further securely holding same in itsvertical position.

FIG. 4 illustrates another preferred embodiment of the invention, inwhich the duct 10 extends horizontally so that its lid 20 is heldvertically in its closed position. The constructions of the lockmechanism 30 and so forth are exactly as set forth during description ofthe preceding embodiment of FIGS. 1 to 3. However, since the lid 20 inthis second embodiment tends gravitationally to turn counterclockwise,as seen in FIG. 4, due to the weight of the lock mechanism 30 and soforth, one or more springs of suitable type are affixed at 104 to theinterior surface of the duct 10 in order to urge the lid 20 in theclockwise direction. Thus, when the latch 31 is moved out of engagementwith the roller 52 by any of the means discussed previously, the lid 20will be duly turned clockwise to its horizontal or open position of FIG.4 thereby causing the smoke and combustion gases to be dischargedthrough the duct 10 with the aid of the blower.

FIGS. 5 to 7 illustrate still another preferred embodiment of theinvention, which includes a lock mechanism 70 mounted on the lid of theduct 10, the lid 20 being turnably supported at the open end of the duct'10 in the manner described previously in connection with the FIGS. 1 to3 embodiment. The lock mechanism 70 includes a latch 72 in the form of arod extending substantially parallel to the plane of the lid 20 througha guide 73 of hollow cylindrical shape securely supported on'astationary mount 71. The latch 72 is yieldably urged to the left, asviewed in FIG. 5, by spring means provided within the hollow cylindricalguide 73, so that its end 72b normally rests on the roller 52 to holdthe lid in its horizontal or closed position. It may be noted from FIG.5 that the bracket 51 rotatably supporting the roller 52 has a slopingsurface 53 extending between the roller 52 and the interior surface ofthe duct 10. Thus, for closing the lid 20 after once opening same, as byway of a performance test which may be conducted periodically, the lidmay simply be turned counterclockwise in FIG. 5 because then the latch72 is caused to retract into the guide 73 as its end 72b moves insliding contact with the sloping surface 53. Urged by the spring meanswithin the guide 73,

the latch 72 will properly. rests on the roller 52 when the lid 20 hasbeen turned to its horizontal position.

The reference numeral 80 generally designates means adapted to convey animpulsive pull to the latch 72 and hence tomove same out of engagementwith the roller 52. The means 80 comprises a support 81 fixedly mountedon the upper surface of the lid 20 and a bell crank or, in thisparticular embodiment, a lever 82 of triangular shape turnably supportedat one of its apices by the support 81. Another apex 82a of the lever 82is connected to the end 72a of the latch 72 by wire 83, whereas theother apex 82b is connected by wire 84 to a weight 91 of means 90adapted to produce the impulsive pull to be conveyed to the latch 72 bythe means 80.

The means 90 comprises the weight 91 connected to the lever 82 by thewire 84 extending through the bore 23 of the lid 20, a rod 92 extendingdownwardly from the lower surface of the lid 20 through the weight 91,

and a cotter pin 93 removably inserted into a transverse 7 hole 95 atthe lower end of the rod 92 projecting from the bottom of the weight 91so that the weight is normally held in its elevated position under thelid 20. The weight 91, generally of cylindrical shape, is partlyhollowed at 91a to house an extra length of the wire 84 and is furtherbored at 94 to receive the rod 92 with suitable clearance. The cotterpin 93 is connected to a grip 97 by wire 96 of high tensile strength andlow elasticity such for example as'piano wire.

In this third preferred embodiment of the invention, constructed ashereinbefore described, the lid 20 in the normal state is held locked inits closed position as the end 7212 of the latch 72 is caused to rest onthe roller 52 by the spring means within the guide 73. The extra lengthof the wire 84 is then held coiled within the hollow space 91a of theweight 91, and the weight 91 is retained in its elevated position by thecotter pin 93.

When, in this condition, the grip 97 is pulled manually, as indicated bythe arrow 0 in FIG. 5, the cotter pin 93 can be disengaged from the rod92 without any great exercise of force. Thereupon the weight 91 isdropped the full extra length of the wire 84 housed in its hollow space91a, and the apex 82a of the lever 82 receives the full impact of thedropped weight through the wire 84. Thus impulsively turning to theposition indicated by the dot-and-dash lines in FIG. 5, the lever 82pulls the latch 72 to the right through the wire 83 against the springmeans within the guide 73. The lock mechanism being now released, thelid 20 is free to turn counterclockwise, as indicated by the arrows b inFIG. 5, to its vertical or open position shown by the dot-and-dash linesin the same drawing.

It will readily occur to those skilled in the art that the cotter pin 93can be disengaged from the rod 92 by means of an electromagnetic unit,perhaps energized manually by a push button switch or automatically by asmoke or fire detector.

Illustrated in FIGS. 8 to 11 is a further preferred em bodiment of theinvention, in which the duct 10, the lid 20, the means 50 and the lockmechanism 70 are all constructed exactly like their respectivecounterparts in the FIGS. 5 to 7 embodiment. The means differs from thecorresponding means 80 of the FIGS. 5 to 7 embodiment only in that theapex 82b of the triangular lever 82 is coupled to an end a of a member85, the other end 85b of which member is bifurcated as in FIG. 10 forpurposes hereinafter made apparent.

The numeral in FIG. 9 generally designates means for applying an impactload to the lever 82 thereby causing same to impulsively turn clockwiseas seen in the drawing and hence to move the latch 72 out of engagementwith the roller 52. The makeup of the means 110 is such that a verticalguide rod 111, fixedly supported at its upper end by a stationary member1 12 secured in a suitable manner to the duct 10, extends with clearancethrough a central bore 113a of the weight 113 and through the bifurcatedend 85b of the member 85. A stop 111a is screw-threadedly affixed to thelower end of the guide rod 111 in order to prevent the detachment of theweight 113. This weight 113 is annularly grooved at l13b adjacent to theupper end thereof, and the portion of the weight above this annular slotis tapered at 1136 as in the drawing.

A horizontal support member 114, having its end 114a bent downwardly,issupported at 114b between the stationary member 112 and the weight 113and is turnable on the guide rod 111. As seen in both FIGS. 9 and 11, astop extending parallel to the support member 114 has its end 115aloosely received in the annular lgroove l13b of the weight 113 toreleasably retain same in its uppermost position on the guide rod 111. Aguide slot 1155 is formed approximately centrally of the stop 115 toloosely receive a projection ll4c extending downwardly from the supportmember 114, the projection 114a having a flange 114d at its lower end toslidably hold the stop 1 15. The other end 1 15c of the stop 1 15 isslidably inserted into an opening ll4e formed through the downwardlybent free end' 114a of the support member 114 and is further connectedby piano wire 118 or the like to a grip l 17, FIG.

8, which may be placed in any suitable position of the building. Ahelical compression spring is provided at 11 6 to resiliently urge thestop 115 toward the weight 113.

When the grip 117 in this fourth preferred embodiment of the inventionis pulled manually, as in the event of a fire, the stop 11'5 moves inthe direction of the arrow a in FIG. 8 against the helical compressionspring 116. The end 115a of the stop 115 being thus disengaged from theannular groove 113b of the weight 113,

the weight drops on the bifurcated end 85b of the member 85 therebyturning the lever 82 clockwise as viewed in FIGS. 8 and 9. The fullimpact of the weight 113 which has dropped on the member 85 at anaccelerated speed is conveyed to the latch 72 of the lock mechanism 70through the wire 83, pulling the latch in the direction of the arrow bin FIG. 8. The lid 20 is now free to turn as indicated by the arrows cin the same drawing to its vertical or open position.

Since the stop 115 together with its support member 114 is turnablearound the guide rod 111, the grip 117 can be positioned in anydirection with respect to the duct 10. Further, since the portion 1130of the weight 113 above its annular slot 113b is tapered upwardly asshown in FIG. 9, the weight after being once dropped onto the member 85,as for a performance test, may simply be manually moved upwardly of theguide rod 1 11 to be arrested in its uppermost position by the stop 115,because then the stop is caused to retract against the helicalcompression spring 116 as its end 115a slides over the tapered portion1136 of the weight 113. The once-opened lid 20 may also be simply turnedcounterclockwise in FIG. 8 to be closed and locked in position, owing tothe provision of the sloping surface 53 as in the FIGS. 5 to 7embodiment.

It is an additionl advantage that the various means constituting thisfourth preferred embodiment of the invention areal] conceiled from theview of the building inhabitants, leaving the appearance of the ceilingsubstantially unimpaired. While the stop 1.15 is caused to drop theweight 113 upon the member 85 by the manual pull of the grip 117 in theillustrated example, it will be apparent that this can also be done byuse of an electromagnetic unit which may be energized manually by a pushbutton switch or automatically by a smoke or fire detector.

FIG. 12 shows a modification of the stop 115 and the means more or lessdirectly associated therewith in the FIGS. 8 to 11 embodiment. Ahorizontal support member 120 is turnably mounted at one end thereof onthe guide rod 111 and includes the portion 114 extending downwardlytherefrom to slidably support the stop 1 15. Resiliently urged by ahelical compression spring 123 toward the guide rod 111, the stop 115has its end 122 normally received in the annular groove 113b of theweight 113 to hold same in its uppermost position of the guide rod 111.The other end of the stop 115 is coupled directly to a lever 121extending through a guide slot 124 formed in the support member 120adjacent to the free end thereof. The free end of the lever 121 isconnected by the wire 118 to the grip 117 shown in FIG. 8.

Thus, when the grip 117 is pulled manually, the lever 121 will be turnedclockwise as seen in FIG. 12 through the wire 118 thereby causing thestop 115 to move against the helical compression spring 123 out ofengagement with the annular groove 113b of the weight 113. The weightdrops upon the bifurcated end of the member 85 shown in FIGS. 8 to 10.Thereafter, the lid 20 closing the open end of the duct as in FIG. 8will be opened through the procedure discussed previously in connectionwith the FIGS. 8 to 11 embodiment.

While the embodiments of this invention as disclosed herein are wellcalculated to accomplish the various explicitly stated and implicitlysuggested objects of the invention, many modifications thereof willnevertheless occur to those skilled in the art without departing fromthe spirit and scope of the appended claims. It is therefore to beclearly understood that all matter contained in the above description orshown in the accompanying drawings is of an illustrative and not alimitative nature.

I claim: Y 1. In a ventilation system including a smoke duct having anend open to a enclosed space, and a lid openably closing said end of thesmoke duct, an apparatus for quickly opening said lid in the event of afire, comprising:

support means for supporting said lid at said end of said smoke duct insuch a manner that said lid tends gravitationally to turn to an openposition;

lock means for normally holding said lid in a closed position, said lockmeans comprising a latch supported on the back of said lid so as to bemovable between a first position where said latch engages a membersupported on an interior surface of said smoke duct to hold 'said lid intheclosed position and a second position where said latch disengagessaid member to permit said lid to turn gravitationally to the openposition, and spring means adapted to normally hold said latch insaidfirst position; and

release means for moving said latch to said second position against saidspring means, said release means being actuable from a distant positionwithin said enclosed space.

2. The apparatus as defined in claim 1, wherein said release meanscomprises a bell crank turnably mounted on the back of said lid, a firstelongate flexible element extending between said latch and one of thearms of said bell crank, and a second elongate flexible elementextending from the other arm of said bell crank into said enclosed spacethrough an opening formed in said lid.

3. The apparatus as defined in claim 1, wherein said release meansincludes a solenoid fixedly supported on the back of said lid, andwherein said latch extends through said solenoid, said latch being madeof magnetic material, whereby when said solenoid is energized in theevent of a fire said latch is caused to move to said second positionagainst said spring means.

4. The apparatus as defined in claim 1, further including means forlimiting the angle through which said lid is permitted to turn to itsopen position, said means comprising a first rod turnably connected atone end to the interior surface of said smoke duct, and a second rodturnably connected at one end to one end of said lid which is turnableoutwardly of said smoke duct, said first and said second rod beinginterconnected at the other ends so as to be turnable relative to eachother.

5. The apparatus as defined in claim 4, further including second springmeans tending to urge said one end of said lid outwardly of said smokeduct, said duct being so disposed relative to said enclosed space thatsaid lid is held vertically in its closed position.

6. In a ventilation system including a smoke duct having an end open toan enclosed space, and a lid openably closing said end of the smokeduct, an apparatus for quickly opening said lid in the event of a fire,comprismg:

support means for supporting said lid at said end of said smoke duct insuch a manner that said lid tends gravitationally to turn to an openposition,

said lid being held horizontally when in a closed position; I

lock means for normally holding said lid in the closed position, saidlock means comprising a latch supported on the back of said lid so as tobe movable between a first position where said latch engages a membersupported on an interior surface of said smoke duct to hold said lid inthe closed position and a second position where said latch disengagessaid member to permit said lid to turn gravitationally to the openposition, and spring means adapted to normally hold said latch in saidfirst position; and I impulsive release means for impulsively movingsaid latch to said second position against said spring means by theimpact of a dropped weight, said impulsive release means being actuablefrom a distant position within said enclosed space.

7. The apparatus as defined in claim 6, wherein said impulsive releasemeans comprises a lever of substantially triangular shape turnablysupported at one of its apices on the back of said lid, a first elongateflexible element extending between a second apex of said lever and saidlatch, a second elongate flexible element extending between a third apexof said lever and said weight through said lid, said second elongateflexible element including an extra length loosely housed in a hollowspacewithin said weight when same is in an elevated position, weightretaining means for releasably retaining said weight in the elevatedposition, and a third elongate flexible element extending from saidweight retaining means to a position within easy reach of an operator,said weight being permitted to drop the full extra length of said secondelongate flexible element when said weight retaining means is operatedthrough said third elongate flexible element, thereby causing said latchto move to said second position by the impulsive turn of said lever.

8. The apparatus as defined in claim 7, wherein said weight retainingmeans comprises a stationary member extending downwardly from the frontsurface of said lid and loosely received in a first bore formed throughsaid weight when same is in the elevated position, and a pin removablyinserted into a second bore formed through the lower end of saidstationary member projecting from said first bore to normally retainsaid weight in the elevated position, said pin being connected to oneend of said third elongate flexible element.

9. The apparatus as defined in claim 6, further in- I eluding a slopingsurface extending between said member and said interior surface of saidsmoke 'duct such that said latch moves in sliding contact therewith toits first position when said lid is closed manually after being once'opened.

'weight in an elevated position as determined by said guide means, and asecond elongate flexible element extending from said weight retainingmeans to a position within easy reach of an operator, said weight beingpermitted to drop substantially on said third apex of said lever asguided by said guide means when said weight retaining means is operatedthrough said second elongate flexible element.

11. The apparatus as defined in claim 10, wherein said weight retainingmeans comprises a stop supported within said duct so as to be movablebetween a first position where one end of said stop engages said weightto hold same in the elevated position and a second position where saidstop disengages said weight to permit same to drop as guided by saidguide means, the other end of said stop being connected to one end ofsaid second elongate flexible element, and spring means adapted tonormally hold said stop in its first position.

12. The apparatus as defined in claim 11, wherein said stop is turnablearound said weight, and wherein a groove is formed circumferentially ofsaid weight to permit engagement thereof by said one end of said stop inany position around said weight, whereby said second elongate flexibleelement is permitted to extend in any direction with respect to saidweight.

13. The apparatus as defined in claim 12, wherein the portion of saidweight above said groove is tapered upwardly whereby said one end ofsaid stop slides over said tapered portion to its first position whensaid weight'is raised manually to its elevated position after being oncedropped.

14. The apparatus as defined in claim 10, wherein said weight retainingmeans comprises a stop supported 'within said duct so as to bemovablebetween a first position where one end of said stop engages saidweight to hold same in the elevated position and a second position wheresaid stop disengages said weight to permit same to drop as guided bysaid guide means, a lever connected to the other end of said stop and toone end of said second elongate flexible element to transmit the motionof the latter to the former, and spring means adapted to normally holdsaid stop in its first position.

1. In a ventilation system including a smoke duct having an end open toa enclosed space, and a lid openably closing said end of the smoke duct,an apparatus for quickly opening said lid in the event of a fire,comprising: support means for supporting said lid at said end of saidsmoke duct in such a manner that said lid tends gravitationally to turnto an open position; lock means for normally holding said lid in aclosed position, said lock means comprising a latch supported on theback of said lid so as to be movable between a first position where saidlatch engages a member supported on an interior surface of said smokeduct to hold said lid in the closed position and a second position wheresaid latch disengages said member to permit said lid to turngravitationally to the open position, and spring means adapted tonormally hold said latch in said first position; and release means formoving said latch to said second position against said spring means,said release means being actuable from a distant position within saidenclosed space.
 2. The apparatus as defined in claim 1, wherein saidrelease means comprises a bell crank turnably mounted on the back ofsaid lid, a first elongate flexible element extending between said latchand one of the arms of said bell crank, and a second elongate flexibleelement extending from the other arm of said bell crank into saidenclosed space through an opening formed in said lid.
 3. The apparatusas defined in claim 1, wherein said release means includes a solenoidfixedly supported on the back of said lid, and wherein said latchextends through said solenoid, said latch being made of magneticmaterial, whereby when said solenoid is energized in the event of a firesaid latch is caused to move to said second position against said springmeans.
 4. The apparatus as defined in claim 1, further including meansfor limiting the angle through which said lid is permitted to turn toits open position, said means comprising a first rod turnably connectedat one end to the interior surace of said smoke duct, and a second rodturnably connected at one end to one end of said lid which is turnableoutwardly of said smoke duct, said first and said second rod beinginterconnected at the other ends so as to be turnable relative to eachother.
 5. The apparatus as defined in claim 4, furtheR including secondspring means tending to urge said one end of said lid outwardly of saidsmoke duct, said duct being so disposed relative to said enclosed spacethat said lid is held vertically in its closed position.
 6. In aventilation system including a smoke duct having an end open to anenclosed space, and a lid openably closing said end of the smoke duct,an apparatus for quickly opening said lid in the event of a fire,comprising: support means for supporting said lid at said end of saidsmoke duct in such a manner that said lid tends gravitationally to turnto an open position, said lid being held horizontally when in a closedposition; lock means for normally holding said lid in the closedposition, said lock means comprising a latch supported on the back ofsaid lid so as to be movable between a first position where said latchengages a member supported on an interior surface of said smoke duct tohold said lid in the closed position and a second position where saidlatch disengages said member to permit said lid to turn gravitationallyto the open position, and spring means adapted to normally hold saidlatch in said first position; and impulsive release means forimpulsively moving said latch to said second position against saidspring means by the impact of a dropped weight, said impulsive releasemeans being actuable from a distant position within said enclosed space.7. The apparatus as defined in claim 6, wherein said impulsive releasemeans comprises a lever of substantially triangular shape turnablysupported at one of its apices on the back of said lid, a first elongateflexible element extending between a second apex of said lever and saidlatch, a second elongate flexible element extending between a third apexof said lever and said weight through said lid, said second elongateflexible element including an extra length loosely housed in a hollowspace within said weight when same is in an elevated position, weightretaining means for releasably retaining said weight in the elevatedposition, and a third elongate flexible element extending from saidweight retaining means to a position within easy reach of an operator,said weight being permitted to drop the full extra length of said secondelongate flexible element when said weight retaining means is operatedthrough said third elongate flexible element, thereby causing said latchto move to said second position by the impulsive turn of said lever. 8.The apparatus as defined in claim 7, wherein said weight retaining meanscomprises a stationary member extending downwardly from the frontsurface of said lid and loosely received in a first bore formed throughsaid weight when same is in the elevated position, and a pin removablyinserted into a second bore formed through the lower end of saidstationary member projecting from said first bore to normally retainsaid weight in the elevated position, said pin being connected to oneend of said third elongate flexible element.
 9. The apparatus as definedin claim 6, further including a sloping surface extending between saidmember and said interior surface of said smoke duct such that said latchmoves in sliding contact therewith to its first position when said lidis closed manually after being once opened.
 10. The apparatus as definedin claim 6, wherein said impulsive release means comprises a lever ofsubstantially triangular shape turnably supported at one of its apiceson the back of said lid, a first elongate flexible element extendingbetween a second apex of said lever and said latch, guide means forguiding the motion of said weight such that said weight will dropsubstantially on a third apex of said lever to cause said latch to moveto said second position by the impulsive turn of said lever, weightretaining means for releasably holding said weight in an elevatedposition as determined by said guide means, and a second elongateflexible element extending from said weight retaining means to aposition within easy rEach of an operator, said weight being permittedto drop substantially on said third apex of said lever as guided by saidguide means when said weight retaining means is operated through saidsecond elongate flexible element.
 11. The apparatus as defined in claim10, wherein said weight retaining means comprises a stop supportedwithin said duct so as to be movable between a first position where oneend of said stop engages said weight to hold same in the elevatedposition and a second position where said stop disengages said weight topermit same to drop as guided by said guide means, the other end of saidstop being connected to one end of said second elongate flexibleelement, and spring means adapted to normally hold said stop in itsfirst position.
 12. The apparatus as defined in claim 11, wherein saidstop is turnable around said weight, and wherein a groove is formedcircumferentially of said weight to permit engagement thereof by saidone end of said stop in any position around said weight, whereby saidsecond elongate flexible element is permitted to extend in any directionwith respect to said weight.
 13. The apparatus as defined in claim 12,wherein the portion of said weight above said groove is tapered upwardlywhereby said one end of said stop slides over said tapered portion toits first position when said weight is raised manually to its elevatedposition after being once dropped.
 14. The apparatus as defined in claim10, wherein said weight retaining means comprises a stop supportedwithin said duct so as to be movable between a first position where oneend of said stop engages said weight to hold same in the elevatedposition and a second position where said stop disengages said weight topermit same to drop as guided by said guide means, a lever connected tothe other end of said stop and to one end of said second elongateflexible element to transmit the motion of the latter to the former, andspring means adapted to normally hold said stop in its first position.